Multiple conductor insulated wire



J 1952 R. H. DUDLEY m-AL MULTIPLE CONDUCTOR INSULATED WIRE Filed March 30, 1948 Patented Jan. 8, 1952 UNITED STATES PATENT OFFICE son, Hamden, Conn., assignors to The-Whitney BlakeCompany, Hamden, Com-1;, a corporation of Connecticut AppIicatiOXfMarChBO, 1948,.Serial No. 17,898

"The present invention relates'to improvements in insulated electric cords'or wires andrelates more particularly ,to the type comprising "two or more electric conductors physically bondeditogether but insulated from each other byariinner sheath of insulating material which latter, in turn, is enveloped by an outer sheath of insulating material. Telephone drop wire'a-daptedfor outdoor service is a particular examplepfisuch cord or wire. ,1" g

Inusing insulated multiple conductor wires of the general character abovereferredto; it. is necessaryto separate the individual electric :conductors from each other together with sufiicient of .the insulation to maintain coverage 'for. each of the said electric conductors, in order that-the said electric conductorsmay be separately connectedto binding-posts, other electric conductors or the like.

In the type of multiple conductor wires referred to, it is both diflicult and time-consuming to 'efiect the separation referred to largely for thereason that in longitudinally slitting the outer sheath, care must ,be taken not to also slit or mutilate the portionsof the inner sheath which res'pec-. tively directly provide insulation for the individual electric conductors. Most often, the outer sheath is so tightly bonded to the inner sheath that the longitudinal slitting of the said outer sheath to any reasonable depth is not suihcient toenable the individual electric conductors to be separated-as before referred to, and the inner insulation is apt to tear off from a given conductor or otherwise become mutilated.

The main object of the present invention is'to provide a .-superior insulated multiple conductor wire having both inner andouter sheathscf the general character referredto but characterized by the ease and facility with which its individual electric conductors may be separated from each other together with the insulation adjacent each thereof. V

with the above and otherobjects in -.-view, as will appear to those skilled in the art from the present disclosure, this invention includes all featuresjn the said disclosure which are novel" over the, prior art.

In the accompanying drawings, in whichrcertain modes of carrying out the present invention are shown for illustrative purposes:

Figure 1 is a perspective view of a fragment of an insulated multiple conductor embodying the present invention, with a portion of the outer sheath broken away;

Fig. 2 is a. fragmental perspective view ofthe 3 Claims. (Cl. 174-117) inner :sheath, 'together'with its pair of electric conductors, shown in the condition which it assumes priorito having the outer sheath'applied thereto; and.

Bis a perspective view of a fragment of theinsulated wire'of Fig. 1 shown as havingits two sheaths of insulation parted to .permit the separation of the two'individual conductors.

The particular insulated multiple .conductor wire herein chosen for purposes of making clear apreferred form of. the present invention, inciudestwo (or' more) electric conductors or wires Wand; H. which .are laterally spaced from each other and "held in such spaced relationship by an inner sheath [2 of insulating material. In the instance showuboth of the conductors are of solidiorm'thoughit is to be understood that each thereof. mayjbe 'iormed of a bundle of small strands as'is acommonpractice in the art. The said insulated wirealsoincludes an outer sheath i3 .which also is formed of suitable insulating material.

.Many materials are suitable for forming both theinnersheath l2 and .the outer sheath l3 such, for instance, .as compounds of natural rubber, neoprene", syntheticrubber, etc. Preferably, the outer. sheath [3 is compounded to have superior weathereresistance as compared to the material from which the inner sheath is formed, which latter need only. be superior in its insulating properties. 1

.The inner sheath I2 is formed in each of its respective opposite sides intermediate the two conductors ,10 and H, =withone of two longitu- -;parting-grooves.l4l...and l5, each of which extends: inadepth hut part way across the .said innersheathtoward .the other parting-groove. The :respecti-ve. .hottoms of the said parting grooves lkandili are separated from each other so that dzhernpposite side walls of the respective parting-grooves are held substantially in contact with each other, thus closing the lateral openings of the respective grooves for the reasons which will presently appear.

By reference to Fig. 2 which shows the inner unit of the wire comprising the inner sheath with its two conductors embedded therein in a condition prior to the application thereto of the outer sheath I3, it will be noted that the longitudinal parting-grooves I4 and I are of substantial widths. When, however, as is preferred, the outer sheath I3 is applied by a usual high-pressure extrusion process, the said inner sheath and particularly its integral coupling-web I6, will be compressed and the parting-grooves will be narrowed down into substantial slit-like form, as is indicated in Fig. l, and will be held in such condition by the circumferential tension of the newly-applied outer sheath I3. Under the conditions just described, the inner surfaces of the outer sheath I3 will bridge over the said partinggrooves without materially entering the same, to thereby avoid having the material of the outer sheath cement the side walls of the said partinggrooves together.

When it is desired to separate the two conductors I 0 and I together with proportionate shares of the inner and outer sheaths I2 and I3, all that is required is to slit the respective opposite sides of the outer sheath in substantial registry with the respective parting-grooves I 4 and I5. Following this slitting, the said conductors I0 and H may be separated by tearing the slender couplingweb I6, as is indicated in Fig. 3. This separation of the conductors I0 and II may be readily and rapidly effected, inasmuch as the inner surface of the outer sheath I3 has merely bridged over each of the parting-grooves J4 and I 5, rather than entering thereinto sufliciently to cement the opposite surfaces of the said parting-grooves together.

Thus, it will be apparent that by the simple expedient of causing the outer sheath I 3 or its equivalent to bridge over the parting-grooves I4 and I 5, rather than entering thereinto, the parting of the two conductors I0 and II, each with its appropriate share of the inner and outer,

sheaths I2 and I3, may be readily and conveniently effected. Such procedure would not be possible were the inner portion of the said outer sheath to be permitted to materially enter and cement the opposite side walls of each of the parting-grooves l4 and I5 together.

After the conductors I0 and I I have been separated as is indicated in Fig. 3, the portions of the inner and outer sheaths I2 and I3 respectively thereon may be stripped ofi in the usual manner, to bare the said conductors for attachment to the other electric conductors, to binding-posts or the like.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

We claim:

1. A multiple conductor insulated wire comprising: substantially parallel electrical conductors spaced from each other; an inner sheath of insulation within which said conductors are embedded and by which they are held in spaced, insulated condition with respect to each other; said 4 inner sheath being formed to provide intermediate respectively adjacent conductors a laterally open, longitudinal parting-groove whose side walls, at an intermediate stage of manufacture of the completed wire, are spaced apart a substantial distance, said groove extending in depth only partway through said inner sheath to leave only a relatively slender, integral, longitudinal coupling-web disposed between adjacent portions of said inner sheath, whereby said side walls of said parting-groove are normally urged into substantially parallel spaced-apart relation by said web; and an outer sheath of insulation laterally enveloping said inner sheath and compressing the same under pressure sufficient to positively deform said web and to hold the respective normally spaced-apart side walls of said partinggroove in contact with each other so as to close the lateral opening of said groove.

2. A multiple conductor insulated wire as defined in claim 1, wherein said inner sheath is formed to provide a pair of opposed parting -v grooves intermediate respectively adjacent conductors which grooves extend inwardly toward. each otheronly part way through said inner sheath.

3. The method of producing a multiple conductor insulated wire which includes the steps of: forming a unit comprising adjacent electrical conductors spaced from each other byembedding said conductors within an inner sheath of insulation; forming, intermediate adjacent conductors.

a laterally open, longitudinal parting-groove of. substantial width which extends in depth only. part-way through said inner sheath to leave a relatively slender, longitudinal coupling-webmtegrally uniting the respective portions of said, inner sheath on opposite sides of said groove,

whereby the side walls of said parting-groove are normally held in substantially parallel spacedapart relation by said web; laterally compressing the aforesaid unit under pressure sufficient to positively deform said web until the side walls of said groove are in substantial contact with each other whereby the lateral opening of said groove is closed; and then applying an outer sheath of insulation over said unit while thus laterally compressed to maintain said unit under compression within said outer sheath in the completed wire.

RAYMOND H. DUDLEY. CARL A. LARSON.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS 

